In state of the art automotive instrumentation, electromechanical (pointer-type) displays are typically mechanized with two-coil air core gauges. Each coil is energized with current to generate a magnetic field and a rotor magnet attached to the pointer aligns the pointer with the resultant magnetic field vector.
Air core gauges are typically driven by a dedicated circuit which energizes the coils to develop predetermined current levels as a function of the desired deflection of the pointer. Assuming an orthogonal orientation of the coils, a given deflection DEFL with respect to a vertical axis is achieved with a vertical coil current proportional to cos(DEFL) and a horizontal coil current proportional to sin(DEFL). By providing for bidirectional current, deflections of up to 360 degrees may be achieved.